1. Field of Invention
This invention relates to missiles. Specifically, the present invention relates missile warheads designed to penetrate hard targets.
2. Description of the Related Art
Missiles are used in a variety of demanding applications ranging from air to air and ground combat applications to structural demolition applications. Such applications often require missiles with warheads that can effectively and consistently penetrate and explode within hard targets and that may be safely transported and stored with minimal explosion danger.
A typical hard target missile includes an explosive warhead enclosed within a steel case. A fuse serves to ignite the explosive warhead following target impact. When a warhead penetrates a target, the fuse detonates a booster charge which in turn detonates the explosives in the warhead. At high target impact velocities and oblique impact angles, existing warheads may experience a slap down effect. The slap down effect causes the missile warhead case to become oval shaped as the missile slaps against the target. As a result, the fuse located in the end of the missile warhead case may become dislodged, preventing warhead detonation. Also, the warhead will often fail to adequately penetrate and destroy a target due to inadequate missile velocity or due to structural feature of the warhead that limit warhead sectional pressure. (Sectional pressure is related to the pressure that a warhead exerts on a target at impact and is expressed in terms of weight per unit area). An example of such a structural feature that can limit the penetration of a warhead is the larger diameter warhead case used on traditional warheads.
To improve warhead target penetration, designers attempted to increase missile velocity. However, this proved expensive and difficult due to missile delivery system limitations and existing missile payload length constraints.
In addition, missiles are often launched from a variety of Navy and Air Force launch platforms. The capacity of these launch platforms acts as a missile design constraint limiting the length and diameter of the missiles.
During worst case storage or transport conditions, the warheads may be exposed to fire or other extreme heat, creating hot spots in the explosive fill. These hot spots may lead to unintentional warhead detonation.
To increase missile safety, designers often employ stress risers. A stress riser is implemented via a groove in the missile case. When the case is exposed to fire or another heat source, the explosives expand and crack the missile case at the groove. The explosives then slowly burn and vent through the crack in the missile case, thereby avoiding undesirable detonation of missile explosives. The stress riser however, acts as a failure joint upon warhead hard target impact. This reduces target penetrating capability.
Hence, a need exists in the art for a safe and cost effective warhead adaptable to existing missile payload sections that can reliably and consistently penetrate a wide variety of hard targets.